【Foxit PDF SDK for Web】如何设置文件打开后默认双页展示？

pdfui.addViewerEventListener(Events.openFileSuccess, function () {
    pdfui.getPDFViewer().then((viewer) => {
        var viewMode = viewer.getViewModeManager();
        var curViewModeName = viewMode.currentViewMode.getName();
        console.log(curViewModeName);
        if (curViewModeName != "facing-page-view-mode") {
            viewMode.switchTo('facing-page-view-mode');
            // viewMode.switchTo('multipage-view-mode');
            // viewMode.switchTo('continuous-view-mode');
        }
    })
});